Nav: Home

Gold-plated crystals set new standard for natural gas detectors

April 06, 2017

DURHAM, N.C. -- Materials scientists and engineers have developed a sensor that is fast, sensitive and efficient enough to detect specific wavelengths of electromagnetic energy while on the move. The technology could actively scan areas for methane or natural gas leaks, monitor the health of vast fields of crops or quickly sort plastics for recycling.

Working closely with the optoelectronic materials company SRICO, engineers from Duke University have built a prototype detector that beats the existing competition in size, weight, power, speed and, most importantly, cost.

The new technology relies on metamaterials -- engineered structures made of carefully designed repeating cells that can interact with electromagnetic waves in unnatural ways. By combining seemingly simple patterns of metal with extremely thin slices of perfect crystals, the engineers created a streamlined device able to detect invisible infrared signatures emitted by various kinds of gasses, plastics and other sources.

The results appeared on February 20, 2017, in the journal Optica.

"The benefit of using metamaterials is that different components required in a detector can be combined into one feature," said Willie Padilla, professor of electrical and computer engineering at Duke. "That simplification gains you a lot of efficiency."

In a typical thermal detector, infrared light waves are absorbed and converted into heat by a black substance, essentially soot. That heat is conducted to a separate component that creates an electrical signal that is then read out. This setup creates speed limitations, and only by overlaying filters or a complex system of moving mirrors, can specific wavelengths be singled out.

The new metamaterial sensor skirts both of these issues.

Each tiny section of the detector consists of a pattern of gold sitting on top of lithium niobate crystal. This crystal is pyroelectric, meaning that when it gets hot, it creates an electrical charge. Like shaving a piece of cheese off a block, engineers at SRICO use an ion beam to peel a slice of crystal just 600 nanometers thick. This technique eliminates potential defects in the crystalline structure, which reduces background noise. It also creates a thinner slice than other approaches, allowing the crystal to heat up more quickly.

Ordinarily, this crystal is so thin that light would simply travel through without being absorbed. However, researchers tailor the top layer of gold into a pattern that combines with the properties of the crystal to cause the pixel to absorb only a specific range of electromagnetic frequencies, removing the need for separate filters. When the crystal heats up and generates an electric charge, the gold then does double duty by carrying the signal to the detector's amplifier, eliminating the need for separate electrical leads.

"These designs allow this technology to be 10 to 100 times faster than existing detectors because the heat is created directly by the crystal" said Jon Suen, a postdoctoral associate in Padilla's laboratory. "This lets us create devices with fewer pixels and also presents the ability to sweep the detector across an area or capture images in motion."

"This is such a good marriage of technologies," said Vincent Stenger, an engineer at SRICO and coauthor of the paper. "Working with Duke has been one of the most ideal situations I've had with technology transfer. We can focus on making the material and they can focus on the device structure. Both sides have been contributing with a clear product in mind that we're now working on marketing."

The researchers can fabricate the device to detect any specific range of electromagnetic frequencies simply by redesigning the details of the gold pattern.

Stenger and his colleagues at SRICO have already created a single-pixel prototype as a proof of concept. They are currently working to find funding from industry investors or possibly a follow-on government grant.

The researchers are optimistic as their device has many advantages over existing technologies. Its fast detection time would allow it to quickly scan over an area while looking for methane or natural gas leaks. The simplicity of its design makes it lightweight enough to carry into fields to assess the health of agricultural crops.

"You could even make this into a low-cost lab instrument for spectroscopy for medical samples," said Padilla. "I'm not sure what the eventual price point would be, but it'd be a lot less than the $300,000 instrument we currently have in our laboratory."
-end-
This research was supported by the U.S. Army Research Laboratory (W311SR-14-C-0006).

Jonathan Y Suen, Kebin Fan, John Montoya, Christopher Bingham, Vincent Stenger, Sri Sriram, Willie J. Padilla. "Multifunctional metamaterial pyroelectric infrared detectors." Optica, 2017. DOI: 10.1364/OPTICA.4.000276

Duke University

Related Gold Articles:

As electronics shrink to nanoscale, will they still be good as gold?
As circuit interconnects shrink to nanoscale, will the pressure caused by thermal expansion when current flows through wires cause gold to behave more like a liquid than a solid -- making nanoelectronics unreliable?
Peppered with gold
Terahertz waves are becoming more important in science and technology.
No need to dig too deep to find gold!
Why are some porphyry deposits rich in copper while others contain gold?
An 18-carat gold nugget made of plastic
ETH researchers have created an incredibly lightweight 18-carat gold, using a matrix of plastic in place of metallic alloy elements.
What happens to gold nanoparticles in cells?
Gold nanoparticles, which are supposed to be stable in biological environments, can be degraded inside cells.
Turning 'junk' DNA into gold
Mining the rich uncharted territory of the genome or genetic material of a cancer cell has yielded gold for Princess Margaret scientists: new protein targets for drug development against prostate cancer.
Mathematicians find gold in data
Russian mathematicians and geophysicists have made a standard technique for ore prospecting several times more effective.
Actively swimming gold nanoparticles
Bacteria can actively move towards a nutrient source -- a phenomenon known as chemotaxis -- and they can move collectively in a process known as swarming.
Gold for silver: A chemical barter
From effective medicines to molecular sensors to fuel cells, metal clusters are becoming fundamentally useful in the health, environment, and energy sectors.
Gold for iron nanocubes
Hybrid Au/Fe nanoparticles can grow in an unprecedentedly complex structure with a single-step fabrication method.
More Gold News and Gold Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.